BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem
TTP OnDemand GMAT Video Course
Featured Course

Target Test Prep GMAT OnDemand

Scott Woodbury-Stewart’s private virtual classroom — 400 hours of master-class video lessons for the GMAT Focus Edition.

  • 715+ score guarantee — highest in the industry (99th percentile)
  • 52 chapters · 1,500+ lessons · 4,000+ practice questions
  • 400 hours of video · 1,500+ instructor-led HD smartboard lessons
  • 300,000+ students accepted to Harvard, Stanford, Wharton, Booth & Sloan & more
  • 24/7 live support + weekly Zoom office hours with GMAT instructors
  • TTP AI Assist — 24/7 AI-powered virtual tutor for instant help
  • 1,200+ flashcards + AI-powered study assistant & daily calendar
  • OnDemand, LiveTeach & GMAT Bootcamp formats available
  • Also: GRE, SAT Math & Executive Assessment courses
  • MBA Admissions Consulting now available
  • 🏆 2025 EdTech Breakthrough Award: Test Prep Solution Provider of the Year
  • 200,000+ students served
  • 5-day free trial — $0 to start, no auto-billing, cancel anytime
★★★★★ 5.0 (559 reviews)
130-pt guarantee
$0 to start then $127/mo
Start Free 5-Day Trial Read 559 Reviews →

cube

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 amFollowed by: 2 members
Thanked: 173 times
GMAT Score:710
by gmatmachoman » Wed Apr 21, 2010 1:39 am
A cube is divided into 8 equal cubes. Each of these cubes is further sub-divided into 8 equal
cubes. What is the ratio of the surface area of the smallest cube as a percentage of the original
cube ?


1] 1/16

2] 1/64

3] 1/256

4] 1/4
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Legendary Member
Posts: 576
Joined: Sat Mar 13, 2010 8:31 pmFollowed by: 1 member
Thanked: 97 times

by liferocks » Wed Apr 21, 2010 1:45 am
vol of big cube length of side area of surface
a^3 a 6a^2
a^3/64 a/4 6a^/16

hence ratio of small to big 1/16
1 question...do you want the ratio of the percentage.in the second case smalles cube will have surface wich is 100/16 % or 6.25% of the large one

option 1
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 610
Joined: Fri Jan 15, 2010 12:33 amFollowed by: 2 members
Thanked: 47 times

by kstv » Wed Apr 21, 2010 1:47 am
Let dimesion of original cube be 4 x 4 x 4 = 64

surfaces area = 6 X 4 X 4

smallest cube will be 1 x 1 x 1

surface area = 6

Ratio = 6/6*16 = 1/16
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1275
Joined: Thu Sep 21, 2006 11:13 pmFollowed by: 2 members
Location: Arabian Sea
Thanked: 125 times

by ajith » Wed Apr 21, 2010 1:47 am
gmatmachoman wrote:A cube is divided into 8 equal cubes. Each of these cubes is further sub-divided into 8 equal
cubes. What is the ratio of the surface area of the smallest cube as a percentage of the original
cube ?


1] 1/16

2] 1/64

3] 1/256

4] 1/4
The smallest cube will have 1/4 the side of the big cube as side
The suface area will be = 6*1/4a*1/4 a = 6a^2/16
The surface area of the big cube = 6a^2
ratio = 1/16
[spoiler]1) [/spoiler]
Always borrow money from a pessimist, he doesn't expect to be paid back.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Master | Next Rank: 500 Posts
Posts: 148
Joined: Tue Jun 09, 2009 11:06 pm
Thanked: 7 times

by pops » Wed Apr 21, 2010 1:57 am
When you make 8 cubes from 1 imagine you divide one cube in two parts and each part is then divided in 4. Hence, each side of the smaller cubes is 1/2 of original cube.
So after second division into further 8 cubes sides are reduced to 1/4

surface area of cube=6*side^2
hence ratio = 1/16
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 amFollowed by: 2 members
Thanked: 173 times
GMAT Score:710

by gmatmachoman » Wed Apr 21, 2010 2:04 am
Thanks guys!!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 2326
Joined: Mon Jul 28, 2008 3:54 amFollowed by: 2 members
Thanked: 173 times
GMAT Score:710

by gmatmachoman » Wed Apr 21, 2010 2:05 am
ajith wrote:
gmatmachoman wrote:A cube is divided into 8 equal cubes. Each of these cubes is further sub-divided into 8 equal
cubes. What is the ratio of the surface area of the smallest cube as a percentage of the original
cube ?


1] 1/16

2] 1/64

3] 1/256

4] 1/4
The smallest cube will have 1/4 the side of the big cube as side
The suface area will be = 6*1/4a*1/4 a = 6a^2/16
The surface area of the big cube = 6a^2
ratio = 1/16
[spoiler]1) [/spoiler]
Ajith bhai..

Congrats for your 100 th Thx!! I missed thanking u as the 100 th guy..but 101 is also a nice figure!!
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Legendary Member
Posts: 809
Joined: Wed Mar 24, 2010 10:10 pmFollowed by: 4 members
Thanked: 50 times

by akhpad » Wed Apr 21, 2010 3:00 am
I am fine with the above solution.

But I have one Q.

What is the ratio of the surface area of the smallest cube as a percentage of the original cube ?

What is the role of percentage over here? Above all choices given in ratio only.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1